Construction machine

Abstract

A position/posture computing section determines that an azimuth of an upper swing structure calculated at a GNSS receiver is of low quality when at least one of a posture angle of the upper swing structure acquired at a machine-body IMU and a posture angle of a front work implement acquired at a boom IMU is equal to or larger than a threshold value, executes a bias removal computation on the basis of the quality of the azimuth and the azimuth of the upper swing structure calculated at the GNSS receiver, calculates a corrected azimuth of the upper swing structure on the basis of the azimuth of the upper swing structure calculated at the GNSS receiver, and an angular velocity of the upper swing structure from which a gyro bias has been removed, and computes a three-dimensional position and posture of the front work implement by using the corrected azimuth.

The invention claimed is: 
     
       1. A construction machine comprising:
 a lower travel structure; 
 an upper swing structure that is swingable relative to the lower travel structure; 
 an articulated-type front work implement attached vertically rotatably relative to the upper swing structure; 
 a GNSS system having two GNSS antennas attached to the upper swing structure and a GNSS receiver that calculates three-dimensional coordinates of the GNSS antennas and an azimuth of the upper swing structure on a basis of a satellite signal received by the GNSS antennas; 
 an angular velocity acquiring apparatus that is attached to the upper swing structure and acquires an angular velocity of the upper swing structure; 
 a machine-body posture angle acquiring apparatus that is attached to the upper swing structure and acquires a posture angle of the upper swing structure; 
 a front-implement posture angle acquiring apparatus that acquires a posture angle of the front work implement; and 
 a controller, 
 the controller being configured to compute a position and posture of the front work implement on a basis of the three-dimensional coordinates of the GNSS antennas and the azimuth of the upper swing structure that are calculated at the GNSS receiver, the posture angle of the upper swing structure acquired at the machine-body posture angle acquiring apparatus, the angular velocity of the upper swing structure acquired at the angular velocity acquiring apparatus and the posture angle of the front work implement acquired at the front-implement posture angle acquiring apparatus, and control operation of the front work implement on a basis of the position and posture of the front work implement, wherein 
 the controller is further configured to
 determine quality of the azimuth of the upper swing structure calculated at the GNSS receiver on a basis of at least one of the posture angle of the upper swing structure acquired at the machine-body posture angle acquiring apparatus and the posture angle of the front work implement acquired at the front-implement posture angle acquiring apparatus, 
 execute a bias removal computation of removing a gyro bias from the angular velocity of the upper swing structure acquired at the angular velocity acquiring apparatus on a basis of a result of the determination about the quality of the azimuth and the azimuth of the upper swing structure calculated at the GNSS receiver, and determine presence or absence of swing operation of the upper swing structure on a basis of the angular velocity of the upper swing structure from which the gyro bias has been removed, and 
 calculate a corrected azimuth of the upper swing structure on a basis of the azimuth of the upper swing structure calculated at the GNSS receiver, the angular velocity of the upper swing structure from which the gyro bias has been removed, and a result of the determination about swing operation of the upper swing structure, and compute the position and posture of the front work implement by using the corrected azimuth. 
 
 
     
     
       2. The construction machine according to  claim 1 , wherein
 the machine-body posture angle acquiring apparatus is at least one machine-body inclination sensor attached to the upper swing structure, 
 the front-implement posture angle acquiring apparatus is at least one front-implement inclination sensor attached to the front work implement, and 
 the controller is configured to determine the quality of the azimuth of the upper swing structure calculated at the GNSS receiver on a basis of at least one of the posture angle of the upper swing structure sensed at the machine-body inclination sensor and the posture angle of the front work implement sensed at the front-implement inclination sensor, and execute the bias removal computation when it is determined that the quality of the azimuth of the upper swing structure is deteriorated. 
 
     
     
       3. The construction machine according to  claim 1 , further comprising:
 an image recognizing apparatus as a posture angle acquiring apparatus of at least one of the machine-body posture angle acquiring apparatus and the front-implement posture angle acquiring apparatus, wherein 
 the image recognizing apparatus recognizes at least one of the posture angle of the upper swing structure and the posture angle of the front work implement on a basis of image information acquired from at least one camera, and 
 the controller is configured to determine the quality of the azimuth of the upper swing structure calculated at the GNSS receiver on a basis of at least one of the posture angle of the upper swing structure and the posture angle of the front work implement recognized at the image recognizing apparatus, and execute the bias removal computation when it is determined that the quality of the azimuth of the upper swing structure is deteriorated. 
 
     
     
       4. The construction machine according to  claim 1 , wherein
 the controller
 includes a terrain information storage apparatus storing terrain information around the construction machine thereon, and 
 is configured to
 read in terrain information around the construction machine stored on the terrain information storage apparatus on a basis of the three-dimensional coordinates of the GNSS antennas calculated by the GNSS receiver, and 
 determine, in addition to or instead of the determination about the quality of the azimuth of the upper swing structure based on the posture angle of the upper swing structure acquired at the machine-body posture angle acquiring apparatus and the posture angle of the front work implement acquired at the front-implement posture angle acquiring apparatus, that the azimuth of the upper swing structure calculated at the GNSS receiver is of low quality when there is a possibility that terrain around the construction machine interrupts a satellite signal receivable area of the GNSS antennas, and execute the bias removal computation. 
 
 
 
     
     
       5. The construction machine according to  claim 1 , wherein
 the controller
 includes an azimuth storage apparatus that stores an azimuth of the upper swing structure when the azimuth has been determined as being of high quality, and 
 is configured to compute the position and posture of the front work implement by using, as a corrected azimuth, an azimuth that is stored on the azimuth storage apparatus immediately before an azimuth of the upper swing structure is determined as being of low quality, when it is determined that the azimuth of the upper swing structure is of low quality and it is determined that there is no swing operation of the upper swing structure. 
 
 
     
     
       6. The construction machine according to  claim 1 , wherein
 the controller is configured to notify a user that there is a possibility that precision of the azimuth of the upper swing structure is low when predetermined time period has elapsed while the quality of the azimuth of the upper swing structure has remained low after it is determined that the azimuth of the upper swing structure is of low quality and it is determined that there is swing operation of the upper swing structure. 
 
     
     
       7. The construction machine according to  claim 1 , further comprising:
 a first operation lever device that gives an instruction for operation of the front work implement, wherein 
 the controller is configured to, when a determination is to be made about the quality of the azimuth of the upper swing structure calculated at the GNSS receiver, receive, as input, an operation signal of the first operation lever device as a backup of the posture angle of the front work implement acquired at the front-implement posture angle acquiring apparatus, and determine, on a basis of the operation signal of the first operation lever device, that the azimuth of the upper swing structure is of low quality when raising-direction operation of the front work implement by the first operation lever device is continued for predetermined time period or longer. 
 
     
     
       8. The construction machine according to  claim 1 , further comprising:
 a second operation lever device that gives an instruction for operation of the upper swing structure, wherein 
 the controller is configured to, when a determination is to be made about presence or absence of swing operation of the upper swing structure, receive, as input, an operation signal of the second operation lever device as a backup of the angular velocity of the upper swing structure from which the gyro bias has been removed and determine, on a basis of the operation signal of the second operation lever device, that there is swing operation of the upper swing structure when a magnitude of the operation signal of the second operation lever device is equal to or larger than a predetermined value.